There are many occasions when a control lever is required to have a two position toggle action, so that a function controlled by the lever can either be ON or OFF. A conventional manner in which this is achieved is to connect a coil spring to the lever and to the support bracket on which the lever is pivoted. The positions of the anchoring points of the ends of the spring are selected in such a manner that the distance between them increases and then decreases as the lever is moved from one end position to the other, to provide the desired toggle action.
A problem is encountered in the prior art in that on certain occasions there is not sufficient space to accommodate a coil spring. In particular, when the lever is short, the spring must have a sufficiently large diameter to exert a sufficient force on the lever. The difficulty in accommodating a spring of large diameter is aggravated by the need to keep the entire volume swept by the coil spring while moving from one position to the other free of any obstruction.
Other known solutions, such as providing a spring biased cam follower mechanism to act between the lever and its support also require additional space to accommodate them and need additional components which add to the complexity and cost.